linux-kernel - Possible deadlock when suspending framebuffer

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Message-ID: <BANLkTiko+2AM8dq8jP5xjbTcCM63hBAK=A@mail.gmail.com>
Date:	Tue, 14 Jun 2011 15:10:49 +0200
From:	Francis Moreau <francis.moro@...il.com>
To:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Possible deadlock when suspending framebuffer

Hello,

I noticed that a possible deadlock can happen when the current frame
buffering is being suspended and a new frambuffer device is being
registred at the same time.

When suspending the current frambuffer by doing : echo 1
>/sys/class/graphics/fb0/state, the kernel actually takes the
following locks in that order: console_lock, lock_fb_info (see
store_fbstate()).

However when a new framebuffer is coming in, the lock sequence is:
lock_fb_info (taken by do_remove_conflicting_framebuffer()),
console_lock() (taken by unbind_console).

I don't know how this should be fixed though...

Thanks
-- 
Francis
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